In a communication system, a communication session can be arranged by means of a node and a gateway. Control parameters are commonly signaled for the communication session from the node to the gateway. In the method the gateway is provided with information about the capabilities of the node. A decision in made if at least one of the control parameters for the communication session needs to be changed. If so, the new value of the at least one control parameter is determined based on information of the capabilities of the node. The node is then informed about the changed value of the least one control parameter. The communication session can then be controlled based on the changed value of the at least one control parameter.